(defclass food ()
  ((name
    :initarg :name)
   (calories
    :initarg :calories)
   (portion-size
    :initarg :portion-size)))

(defvar *data*
  (list (make-instance 'food
                       :name "banana"
                       :calories 100
                       :portion-size 200)
        (make-instance 'food
                       :name "apple"
                       :calories 150
                       :portion-size 100)))

(defvar *x* (first *data*))

(defmacro with-dataframe (sym &body body)
  (let ((names (mapcar #'sb-mop:slot-definition-name
                       (sb-mop:class-direct-slots (class-of *x*)))))
    `(symbol-macrolet (,@(mapcar (lambda (n)
                                   `(,n (slot-value ,sym ',n)))
                                 names))
       ,@body)))